drop sequence seq_customer_id;
CREATE SEQUENCE seq_customer_id START WITH 1 INCREMENT BY 1;
CREATE OR REPLACE TRIGGER BI_CUSTOMER_ID
BEFORE INSERT ON customerdetails
FOR EACH ROW
BEGIN
    SELECT replace('C'||to_char(SEQ_customer_ID.NEXTVAL,'099'),' ',''),sysdate INTO :NEW.user_id,:NEW.start_date FROM DUAL;
END;
